JP3769581B1 - Polishing pad and manufacturing method thereof - Google Patents

Abstract

A polishing pad that is particularly effective in maintaining an appropriate value of a polishing rate and improving in-plane uniformity after polishing of an object to be polished, and extremely effective in production of chemical mechanical polishing such as a semiconductor wafer, and a method for manufacturing the same I will provide a.
A polishing pad formed of polyurethane foam having a groove 1 in a polishing surface, wherein a processed surface of the groove 1 including a side surface 11 and a bottom surface 12 of the groove has a surface roughness (Ra) of 10 or less. A method for manufacturing a polishing pad, comprising a step of forming a groove having a concentric cross-sectional shape of a rectangle on a polishing surface by stepwise changing a feed rate and a feed amount of a polishing pad and a groove processing blade.
[Selection] Figure 1

Description

  The present invention relates to a polishing pad used for polishing an object to be polished and a method for manufacturing the same, and in particular, in a semiconductor device manufacturing process, planarization treatment of an interlayer insulating film or the like by CMP (chemical mechanical polishing or chemical mechanical polishing). The present invention relates to a polishing pad used when performing the above, and a method of manufacturing the polishing pad.

  In recent years, miniaturization and high integration of semiconductor integrated circuits have rapidly evolved, and it has become necessary to perform fine processing, and devices have become complicated structures and become three-dimensional. Miniaturization is an advance in microfabrication technology in the manufacturing process of a semiconductor device, particularly in a lithography process that is a technique for transferring a circuit pattern to a photosensitive organic film (photoresist) coated on a wafer surface using light. It has been achieved by increasing the resolution. Specifically, a technique for performing exposure using a light source having a shorter wavelength in a lithography process has been developed. In addition, a method is being studied in which the difference in height of the device structure is reduced as much as possible to compensate for the lack of depth of focus and to reliably resolve a fine pattern without causing a defocus.

  Therefore, as a method for flattening the difference in height of the device structure, a CMP method that applies mirror processing of a silicon wafer has been recently adopted. This apparatus is supported by a rotating polishing plate rotating shaft and has a polishing pad on the surface. A polishing plate to which a surface of the polishing pad is made conspicuous, and a polishing object layer (such as an interlayer insulating film) formed with diamond powder or the like formed by electrodeposition on a metal plate. (Hereinafter, referred to as a wafer) by a wafer backing film and a polishing slurry supply device having a polishing slurry supply nozzle for supplying the polishing slurry onto the polishing pad.

  As one method, after dressing (grinding) the polishing pad with a dresser, the polishing pressure is adjusted while rotating the polishing plate rotation shaft and the carrier rotation shaft and supplying the polishing slurry from the polishing slurry supply nozzle to the center of the polishing pad. There is a method of polishing a wafer by pressing the wafer onto a polishing pad by a mechanism. In such a CMP method, there is a problem that microscratches are generated in a layer to be polished such as an insulating film of the wafer, a polishing rate varies, and a polishing amount varies widely within the wafer surface.

  In order to suppress the occurrence of micro-scratch, polishing pad scraping scraps, dresser diamonds, interlayer films, wafer debris and polished polishing slurries generated during dressing of the polishing pad (hereinafter collectively referred to as these) (Also referred to as impurities) must be discharged out of the polishing pad. In such a conventional CMP apparatus, measures are taken such that the polishing slurry is sufficiently flowed to the center of the polishing pad without interruption during the polishing operation, and impurities are removed or pushed out of the polishing pad by this polishing slurry. Thus, when a dressing layer is formed on the pad surface by dressing and the polishing slurry is supplied to polish the wafer, the polishing slurry is pushed out by the centrifugal force due to the rotation of the polishing pad and pressing the wafer against the polishing pad. Is discharged outside the polishing pad without directly contributing to polishing, and therefore, an expensive polishing slurry is consumed in excess.

  In order to solve these problems, a polishing pad for semiconductor device processing and a groove processing tool (see Patent Documents 1 and 2) in which grooves having edges perpendicular to the corner portion of the groove entrance are formed concentrically, and a semiconductor There have been proposed a narrow groove processing machine, a processing tool and a processing method (see Patent Document 3) that form concentric or grid-like narrow grooves on a polishing pad for CMP processing by machining.

  In the polishing pad disclosed in Patent Documents 1 and 2, a groove having an edge perpendicular to the corner portion of the groove inlet is formed concentrically with a specific width, depth, and groove pitch, so that the device processing surface and the pad upper surface are formed. Slurry flow is easy to control, and the suppression of hydroplane phenomenon and the efficiency of planarization by CMP process on the soft metal surface of the device can be expected, but the cross-sectional shape of the groove is unstable and the flow of slurry There is a risk that stable polishing characteristics may not be obtained depending on the pad.

  Even in a polishing pad in which a narrow groove is formed by the groove processing tool disclosed in Patent Document 3, the cross-sectional shape of the groove is unstable, the fluidity of the slurry changes depending on the pad, and stable polishing is likely to occur. The characteristics may not be obtained.

In each of the above-mentioned patent documents, by specifying the shape of the cutting edge for grooving, the edge of the groove corner is made to be a right angle so as not to cause the wall wall to come into contact with the wall. With the shape of the cutting edge alone, there is a fear that it is difficult to obtain stable polishing characteristics.
JP 2001-181649 A JP 2002-184730 A JP 2002-11630 A

  The present invention relates to a polishing pad used when performing planarization processing of an interlayer insulating film or the like by CMP in a semiconductor device manufacturing process and the like, and in the manufacturing method of this polishing pad, generation of scratches, variation or decrease in polishing rate, polishing amount It is an object of the present invention to simultaneously solve problems such as a large variation in the wafer surface, excessive consumption of polishing slurry, and inability to hold an appropriate slurry between the object to be polished and the polishing pad.

  The present invention solves the above problems at the same time, and provides a polishing pad used when performing planarization processing of an interlayer insulating film or the like by CMP in a semiconductor device manufacturing process or the like, and a manufacturing method of the polishing pad. That is, the present invention is a polishing pad formed of foamed polyurethane having a groove in the polishing surface, and the processed surface of the groove comprising the side surface and the bottom surface of the groove has a surface roughness (Ra) of 10 or less. The polishing pad is characterized.

  As another aspect of the present invention, the polishing includes a step of forming concentric grooves having a rectangular cross-sectional shape on the polishing surface by mechanically changing the feed speed and feed amount of the grooving blade in stages. There is a method for manufacturing a pad.

  The polishing pad according to the present invention is preferably used for a polishing pad used when performing planarization processing of an object to be polished by CMP. Scratches are generated, polishing rate is varied or decreased, and the amount of polishing in the wafer surface is reduced. It is intended to solve problems such as large variations, excessive consumption of polishing slurry, and inability to hold an appropriate slurry between the object to be polished and the polishing pad. A polishing pad made of foamed polyurethane having a groove (within the polishing surface), wherein a groove having a surface roughness (Ra) of 10 or less is formed on the processed surface of the groove including the side surface and the bottom surface of the groove. It is.

  In polishing of a semiconductor wafer or the like using the polishing pad of the present invention, the polishing rate varies or decreases, the variation in the polishing amount in the wafer surface, the excessive consumption of the polishing slurry, and the object to be polished and the polishing pad It is particularly effective in simultaneously solving problems such as failure to hold an appropriate slurry between the two and reducing the occurrence of scratches, and is extremely effective in the production of CMP such as semiconductor wafers.

  The polishing pad of the present invention is a polishing pad formed of foamed polyurethane having a groove in the polishing surface, and the processed surface of the groove including the side surface and the bottom surface of the groove has a surface roughness (Ra) of 10 or less. Is formed. Further, the polishing pad manufacturing method of the present invention forms a concentric groove having a rectangular cross-sectional shape on the polishing surface by mechanically cutting the feed speed and feed amount of the grooving blade in stages. It includes a process. Next, the polishing pad of this invention and its manufacturing method are demonstrated concretely using FIGS. FIG. 1 is a schematic cross-sectional view of one embodiment of a groove provided in a polishing layer of a polishing pad of the present invention, and FIG. 2 is one embodiment of a groove provided in a polishing layer of a conventional polishing pad. FIG. However, these drawings are partial schematic views of the grooves of the polishing layer of the polishing pad, and do not show accurate dimensions.

  As shown in FIG. 1, in the polishing pad (1) of the present invention, the processing surface of the groove composed of the side surface (11) and the bottom surface (12) of the groove is required to have a surface roughness (Ra) of 10 or less. However, the surface roughness (Ra) is preferably 1 to 9, more preferably 1 to 5. When the surface roughness (Ra) exceeds 10, the flow of the polishing slurry is deteriorated and aggregation is likely to occur, and impurities are likely to be clogged, so that scratches are generated.

  Further, a defect having a depth of 100 μm or more (100 to 500 μm) or a whisker-like projection having a length of 200 μm or more (200 to 1000 μm) is formed in the groove in the polishing surface of the polishing pad of the present invention. Preferably it is 2 or less per cross section. If there are more than 2 defects or whisker-like protrusions, the flow of the polishing slurry becomes poor and aggregation tends to occur or impurities are easily clogged, so that scratching occurs. The defects and whisker-like projections are obtained by dividing the polishing pad into five in the radial direction and observing the groove cross section with an SEM or the like, confirming both states in the cross section, and determining the defect having the depth or the length. The number of whisker-like protrusions is measured.

  FIG. 3 is a partial schematic view of a cutting edge of one embodiment of a grooving blade used in the method for producing a polishing pad of the present invention. FIG. 4 is a partial schematic view of a cutting edge of a grooving blade used in a conventional polishing pad manufacturing method. As shown in FIG. 3, in the polishing pad manufacturing method of the present invention, the grooves are formed using a method of mechanical cutting using a grooving blade, and concentric grooves having a rectangular cross-sectional shape on the polishing surface. Form. The cutting edge shape of the grooving blade used in the manufacturing method of the polishing pad of the present invention is preferably a rectangle having no lateral clearance angle (c) as seen in a conventional grooving blade as shown in FIG. When using a grooving blade having the above-mentioned lateral clearance angle (c), the groove width to be formed is reduced due to wear of the grooving blade, resulting in variations in the holding amount of the polishing slurry (abrasive), and variations in the polishing rate. Or lead to decline. Also, in the side face shape of the cutting edge, when a grooving blade having a rake angle (d) as shown in a conventional grooving blade as shown in FIG. The contact area with the polished surface is changed, and a desired surface roughness (Ra) of the processed surface of the groove, particularly the bottom surface, cannot be obtained. Therefore, it is preferable that the grooving blade used in the manufacturing method of the polishing pad of the present invention has a blade edge shape as shown in FIG. 3 that does not have the side clearance angle (c) or the rake angle (d).

  In the manufacturing method of the polishing pad of the present invention, it is a requirement that the cutting is performed by changing the feed speed and feed amount of the grooving blade stepwise. In this specification, “changing the feed rate and feed amount of the grooving blade stepwise” means that the feed rate and feed amount are divided into stages while one of the concentric grooves is formed. The feed rate value at each stage may increase sequentially, decrease sequentially, increase or decrease, and the time at each stage may be the same. Means it may be different.

  The feed speed of the grooving blade is 0.01 to 0.10 m / min, preferably 0.01 to 0.08 m / min, more preferably 0 while forming one of the concentric grooves. In the range of 0.01 to 0.05 m / min, it is desirable to change it to 1 to 2 steps, preferably 2 to 3 steps, more preferably 2 to 5 steps. If the feed speed of the grooving blade is less than 0.01 m / min, it will increase the machining time and promote blade wear. If it is greater than 0.10 m / min, the burr will increase, the burden on the cutter will increase, Causes instability.

  Further, when the groove forming blade is formed at a constant low speed, the groove forming blade wear increases and the processing time increases. Therefore, the feed speed is preferably increased stepwise. . Further, a time for stopping the feeding of the grooving blade at a position where the grooving blade reaches the deepest part of the groove, that is, a desired groove depth at the time of grooving, that is, the feed speed of the grooving blade is set to 0. It is desirable to provide time for The time for stopping the feeding of the grooving blade is 0.5 to 5 seconds, preferably 1.0 to 3.0 seconds, and if it exceeds 5 seconds, the wear of the cutting blade increases, and the time is longer than 0.5 seconds. If it is short, it becomes difficult to maintain a stable groove shape and surface state.

  As described above, by changing the feed speed of the grooving blade stepwise, the feed amount of the grooving blade also changes stepwise similarly. Further, the total feed amount of the grooving blade varies depending on the desired groove depth, but it is desirable to change it stepwise similarly to the feed rate.

  As described above, in the manufacturing method of the polishing pad of the present invention, the surface of the groove processing surface is formed by forming concentric grooves on the polishing surface by changing the feed speed and the feed amount of the groove processing blade stepwise. The roughness (Ra) can be reduced to 10 or less, and burrs on the pad surface due to the groove processing are reduced, and the cross-sectional shape of the groove can be made a desired rectangle. When the surface roughness (Ra) of the groove processing surface is large, the polishing slurry and the flow of impurities are deteriorated as described above, and scratches are generated. Further, by using the polishing pad manufacturing method of the present invention, not only the edge of the groove entrance becomes a right angle by reducing the burr on the pad surface by the groove processing as shown in FIG. 1, but also the side surface (11 ) And the bottom surface (12) are perpendicular to each other, and the cross-sectional shape of the groove can be stably made a beautiful rectangle. By these, in the polishing pad obtained by the manufacturing method of the polishing pad of the present invention, the shape of the groove formed on the polishing surface is stabilized, and the holding amount of the polishing slurry is stabilized. A large amount of variation in the surface of the wafer can solve the excessive consumption of the polishing slurry, and it is possible to hold an appropriate slurry between the object to be polished and the polishing pad.

  In the polishing pad of the present invention, the width, depth and pitch of the groove are not particularly limited as long as the cross-sectional shape of the groove is stable and beautiful as described above, but 0.2 mm to 5 mm. It is only necessary to have a width of about 0.0 mm, a depth of about 0.2 mm to 4.0 mm, and a pitch of about 0.5 to 6.0 mm, and in accordance with the object to be polished, the polishing method and the polishing conditions from these ranges Can be selected as appropriate. In the present invention, the widths of the concentric grooves are preferably the same, the depths are preferably the same, and the pitches are preferably the same. In this case, the polishing rate can be easily controlled, and at the time of manufacture. The convenience is excellent.

  The polishing pad in the present invention may be a single layer type pad generally used in the past, or a hard surface layer that comes into contact with an object to be polished such as a wafer and an elastic support positioned between the hard surface layer and the platen. It may be a laminated pad having at least two layers, or may be a laminated polishing pad such as a multilayer polishing pad in which other layers are stacked. In view of production and performance, those having at least two elastic support layers located between the hard surface layer and the platen (surface plate) are preferable. Thus, the present invention is not limited to a single-layer or multi-layer polishing pad.

  In the laminated polishing pad, a hard surface layer and an elastic support layer are roughly divided and formed according to the hardness of the hard surface layer (according to JIS K6253-1997. 2 cm × 2 cm (thickness: A sample cut into a size of (optional) was used as a sample for hardness measurement, and allowed to stand for 16 hours in an environment of a temperature of 23 ° C. ± 2 ° C. and a humidity of 50% ± 5%. The hardness was measured using a hardness meter (Asker D-type hardness meter manufactured by Kobunshi Keiki Co., Ltd.). When the hardness is less than 45 degrees, the planarity (flatness) of the object to be polished is deteriorated. When the hardness is more than 65 degrees, the planarity is good, but the uniformity (uniformity) of the object to be polished is deteriorated. End up. The hardness of the elastic support layer (according to JIS K6253-1997, Asker A hardness meter manufactured by Kobunshi Keiki Co., Ltd.) is preferably 25 to 100, more preferably 30 to 85. The thickness of the hard surface layer is preferably 0.2 to 4 mm, more preferably 0.8 to 3.0 mm, and the thickness of the elastic support layer is preferably 0.5 to 2.5 mm, more preferably 1. It is desirable to set it as 0.0-2.0 mm.

  In the single-layer polishing pad, the thickness is about 1.0 to 5.0 mm, and the material may be appropriately selected from materials used for the hard surface layer and the elastic support layer, respectively.

  In the laminated polishing pad, the hard surface layer is preferably an acrylate-based photocurable resin, polyurethane such as non-foamed polyurethane or foamed polyurethane, and the elastic support layer is preferably polyethylene foam, polyurethane foam, polyester non-woven fabric, or the like. It is not a thing. When the hard surface layer and the elastic support layer are formed of a nonwoven fabric, the nonwoven fabric may be impregnated with an impregnating agent such as polyurethane resin. However, the polishing pad may be made of a material other than the above as long as the hardness range is satisfied. In the present invention, a particularly preferred hard surface layer material is a foamed polyurethane resin.

  When a polyurethane resin is foamed, the foaming method can be shared by foaming with a chemical foaming agent, foaming that mixes mechanical foam, and mixing of a hollow body or a precursor that becomes a microhollow body by heat. There may be. By these foaming methods, a fine foam used for the polishing pad in the present invention is obtained.

  The polyurethane resin is composed of an isocyanate-terminated urethane prepolymer and an organic diamine compound, and the isocyanate-terminated urethane prepolymer is composed of a polyisocyanate, a high molecular polyol, and a low molecular polyol. Examples of the polyisocyanate include 2,4- and / or 2,6-diisocyanatotoluene, 2,2′-, 2,4′- and / or 4,4′-diisocyanatodiphenylmethane, 1,5- Naphthalene diisocyanate, p- and m-phenylene diisocyanate, dimeryl diisocyanate, xylylene diisocyanate, diphenyl-4,4′-diisocyanate, 1,3- and 1,4-tetramethylxylidene diisocyanate, tetramethylene diisocyanate, 1,6 Hexamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (= isophorone diisocyanate), bis (4-isocyanatocyclohexyl) methane (= hydrogenated MDI), 2- and 4-isocyanatocyclohexyl-2′-isocyanatocyclohexylmethane, 1,3- and 1,4-bis- (isocyanatomethyl) -cyclohexane Bis- (4-isocyanato-3-methylcyclohexyl) methane, and the like.

  Examples of the polymer polyol include hydroxy-terminated polyesters, polycarbonates, polyester carbonates, polyethers, polyether carbonates, polyester amides, etc. Of these, polyethers and polycarbonates having good hydrolysis resistance are preferable, Polyether is particularly preferable from the viewpoint of price and melt viscosity. Polyether polyols include reaction products of starting compounds having reactive hydrogen atoms with alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin or mixtures of these alkylene oxides. It is done. Examples of the starting compound having a reactive hydrogen atom include water, bisphenol A, and dihydric alcohol for producing a polyester polyol as described below.

  Further, examples of the polycarbonate having a hydroxy group include diols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol and / or polytetramethylene glycol. And the reaction product of phosgene, diallyl carbonate (eg diphenyl carbonate) or cyclic carbonate (eg propylene carbonate). Examples of the polyester polyol include a reaction product of a dihydric alcohol and a dibasic carboxylic acid. In order to improve hydrolysis resistance, a longer distance between ester bonds is preferable. A combination is desirable.

  Although it does not specifically limit as dihydric alcohol, For example, ethylene glycol, 1, 3- and 1, 2- propylene glycol, 1, 4- and 1, 3- and 2, 3- butylene glycol, 1, 6-hexane Glycol, 1,8-octanediol, neopentyl glycol, cyclohexanedimethanol, 1,4-bis- (hydroxymethyl) -cyclohexane, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentane Examples include diol, 2,2,4-trimethyl-1,3-pentanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, and dibutylene glycol.

  As the dibasic carboxylic acid, there are aliphatic, alicyclic, aromatic and / or heterocyclic ones. From the necessity of making the terminal NCO prepolymer to be liquid or low melt viscosity, An alicyclic group is preferred, and in the case of applying an aromatic system, combined use with an aliphatic or alicyclic group is preferred. Examples of these carboxylic acids include, but are not limited to, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid (o-, m-, p-), dimer fatty acids such as oleic acid and the like. These polyester polyols may have a part of carboxyl end groups. For example, a lactone such as ε-caprolactone or a polyester of a hydroxycarboxylic acid such as ε-hydroxycaproic acid can be used.

  Examples of the low molecular polyol include dihydric alcohols used for producing the above-described polyester polyol. The low molecular polyol of the present invention includes diethylene glycol, 1,3-butylene glycol, 3-methyl-1,5. It is preferable to use any one of pentanediol and 1,6-hexamethylene glycol or a mixture thereof. When ethylene glycol or 1,4-butylene glycol, which is a low molecular polyol other than those used in the present invention, is used, the reactivity at the time of cast molding becomes too fast, or the polyurethane abrasive molded product finally obtained Since the hardness becomes too high, the abrasive of the present invention becomes brittle and the IC surface is easily damaged. On the other hand, when a dihydric alcohol having a longer chain than 1,6-hexamethylene glycol is used, the reactivity at the time of cast molding and the hardness of the finally obtained polyurethane abrasive molding can be obtained. Although it is too expensive, it is not practical.

  The isocyanate component is appropriately selected according to the pot life required at the time of cast molding, and the terminal NCO prepolymer to be produced needs to have a low melt viscosity. Therefore, the isocyanate component is used alone or as a mixture of two or more. Applied at. Specific examples thereof include, but are not limited to, 2,4- and / or 2,6-diisocyanatotoluene, 2,2′-, 2,4′- and / or 4,4′-diisocyanate. Natodiphenylmethane, 1,5-naphthalene diisocyanate, p- and m-phenylene diisocyanate, dimeryl diisocyanate, xylylene diisocyanate, diphenyl-4,4'-diisocyanate, 1,3- and 1,4-tetramethylxylidene diisocyanate, Tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (= isophorone) Diisocyanate ), Bis- (4-isocyanatocyclohexyl) methane (= hydrogenated MDI), 2- and 4-isocyanatocyclohexyl-2′-isocyanatocyclohexylmethane, 1,3- and 1,4-bis- (isocyanato) Methyl) -cyclohexane, bis- (4-isocyanato-3-methylcyclohexyl) methane, and the like.

  The organic diamine compound used in the present invention is not particularly limited. For example, 3,3′-dichloro-4,4′-diaminodiphenylmethane, chloroaniline-modified dichlorodiaminodiphenylmethane, 1,2-bis (2-amino) Phenylthio) ethane, trimethylene glycol di-p-aminobenzoate, 3,5-bis (methylthio) -2,6-toluenediamine and the like.

  The average cell diameter of the polishing region made of the fine foam in the present invention is preferably 70 μm or less. A deviation from this range is not preferable because planarity deteriorates.

The specific gravity of the polishing region made of the fine foam in the present invention is preferably 0.5 to 1.0 g / cm ³ . When the specific gravity is less than 0.5 g / cm ^3, the strength of the surface of the polishing region decreases, the planarity (flatness) of the object to be polished deteriorates, and when the specific gravity is greater than 1.0 g / cm ³ , the polishing region Although the number of fine bubbles on the surface tends to be small and planarity is good, it is not preferable because the polishing rate is deteriorated.

  The hardness of the polishing region made of the fine foam in the present invention is preferably 45 to 65 by an Asker D hardness meter. When the D hardness is less than 45 degrees, the planarity (flatness) of the object to be polished is deteriorated. When it is greater than 65 degrees, the planarity is good, but the uniformity (uniformity) of the object to be polished is deteriorated. End up.

  The compressibility of the polishing region made of the fine foam in the present invention is preferably 0.5 to 5.0%. By having a compression ratio in the above range, it is possible to achieve both planarity and uniformity.

  In the present invention, the compression recovery rate of the polishing region made of the fine foam is preferably 50 to 100%. When the compression recovery rate deviates from this range, it is not preferable because a large change appears in the polishing layer thickness and the stability of the polishing characteristics deteriorates as the repeated load applied to the object is applied to the polishing region during polishing. .

  In the present invention, the storage elastic modulus of the polishing region made of the fine foam is preferably 200 MPa or more at a measurement temperature of 40 ° C. and a measurement frequency of 1 Hz. The storage elastic modulus means an elastic modulus measured by applying a sinusoidal vibration to a fine foam using a tensile test jig with a dynamic viscoelasticity measuring apparatus. When the storage elastic modulus is less than 200 MPa, the strength of the surface of the polishing region is lowered, and the planarity (flatness) of the object to be polished is deteriorated.

Specific gravity measuring method It carried out based on JISZ8807-1976. A sample cut into a 4 cm × 8.5 cm strip (thickness: arbitrary) was used as a sample for measuring specific gravity, and allowed to stand for 16 hours in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5%. A hydrometer (manufactured by Sartorius) was used for the measurement.

Hardness measurement was performed in accordance with JIS K6253-1997. A sample cut into a size of 2 cm × 2 cm (thickness: arbitrary) was used as a sample for hardness measurement, and allowed to stand for 16 hours in an environment of a temperature of 23 ° C. ± 2 ° C. and a humidity of 50% ± 5%. At the time of measurement, the samples were overlapped to a thickness of 6 mm or more. The hardness was measured using a hardness meter (Asker D-type hardness meter manufactured by Kobunshi Keiki Co., Ltd.).

Compression rate / compression recovery measurement method Cut into a circle (thickness: arbitrary) with a diameter of 7 mm as a sample for measurement of compression rate / compression recovery rate, in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5% 40 Let stand for hours. For the measurement, a thermal analysis measuring instrument TMA (SS6000 manufactured by SEIKO INSTRUMENTS) was used to measure the compression rate and the compression recovery rate. The calculation formulas for the compression rate and the compression recovery rate are as follows.

[In the formula, T1 is the thickness of the polishing layer when a stress load of 30 KPa (300 g / cm ² ) is maintained for 60 seconds from the unloaded state to the polishing layer, and T2 is 180 KPa (1800 g / cm ² ) from the state of T1. The thickness of the polishing layer when the stress load of 60 seconds is maintained. ]

[In the formula, T1 is the thickness of the polishing layer when a stress load of 30 KPa (300 g / cm ² ) is maintained for 60 seconds from the unloaded state to the polishing layer, and T2 is 180 KPa (1800 g / cm ² ) from the state of T1. The thickness of the polishing layer when the stress load of 60 seconds was held, and T3 was held for 60 seconds in the unloaded state from the state of T2, and then the stress load of 30 KPa (300 g / cm ² ) was held for 60 seconds. It is the polishing layer thickness at the time. ]

  Using the polishing pad of the present invention, while supplying a polishing slurry to the surface of the polishing pad, the object to be polished is rotated while being pressed with a desired polishing pressure, and intersects the moving direction of the polishing pad. The object to be polished is a semiconductor by a method of polishing the surface of the object to be polished by the chemical and mechanical action of the slurry supplied between the surface of the polishing pad and the surface of the object to be polished. The polishing method is a device, and the polishing pad of the present invention is most effective in polishing this semiconductor. The present invention also extends to a method for manufacturing such a polishing pad.

  Examples and the like that specifically show the effects of the present invention will be described below. However, the present invention is not limited to these examples. The evaluation items in Examples and the like were measured as follows.

(Evaluation of polishing characteristics)
SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) was used as a polishing apparatus, and the following polishing characteristics were evaluated using the prepared polishing pad.
(1) Polishing rate The polishing rate was calculated from the time obtained by polishing about 0.5 μm of a 1-μm thermal oxide film formed on an 8-inch silicon wafer. An interference type film thickness measuring device (manufactured by Otsuka Electronics Co., Ltd.) was used for measuring the thickness of the oxide film. As polishing conditions, silica slurry (SS12, manufactured by Cabot) was added as a slurry at 150 ml / min during polishing. The polishing load was 350 g / cm ² , the polishing platen rotation number was 35 rpm, and the wafer rotation number was 30 rpm.

(2) Number of scratches After polishing using a wafer surface inspection apparatus (WM2500) manufactured by Topcon Corporation, the number of scratches (scratches) of 0.5 μm or more on the wafer was measured.

(3) Surface roughness (Ra)
Measurement was performed under the following conditions using a Tencor P-15 surface roughness measuring device.
Scanning length: 2500 μm
Scanning speed: 20 μm / second Probe force: 2 mg
Probe radius: 2.0 μm
Tip angle: 60 °

(4) Groove cross-sectional shape It evaluated using the following evaluation criteria.
Evaluation Criteria ○: When observing the groove cross-sectional shape, the average when measuring the groove width of 3 points (upper, middle, lower) in the depth direction is within the target range, and the groove width is 3 points (upper, middle, A rectangle appears when the variation in (lower) is 30 μm or less or 10% or less of the target width.
Δ: The average groove width is within the target range, but the variation at three groove widths (upper, middle, lower) is larger than 30 μm.
Only a part of the burr is large.
The rectangle appears to some extent, and the variation of the groove width at three points (upper, middle, lower) is 30 μm or less, but the average groove width is slightly outside the target range.
X: The groove width is not within the target range.
There are no rectangles.

(5) Surface burr In the cross section where the groove cross-sectional shape was measured, the burr from the groove to the surface was evaluated using the following evaluation criteria.
Evaluation criteria ○ ... 80 μm or less △… 80-100 μm
× ... 100μm or more

(6) Grooving blade wear Groove processing is performed using a grooving blade with a sharply polished cutting edge, and the state of the cutting edge after processing is confirmed. The R at the corner of the blade edge as shown in FIG. 5 was measured (using a scanning electron microscope (SEM) or a microscope), and the size was evaluated using the following evaluation criteria.
Evaluation criteria ○ ... R: 0 to 0.20 mm (no chipping)
Δ: R: 0.20 to 0.30 mm (or small chipping)
X: R: 0.30 mm or more (or there is a chip size)

Example 1
In a fluorine-coated reaction vessel, 100 parts by weight of a filtered polyether-based prepolymer (Uniroy, Adiprene L-325, isocyanate group concentration: 2.22 meq /), and a filtered silicone-based surfactant (Toray Dow) 3 parts by weight manufactured by Silicone Corporation (SH192) were mixed, and the reaction temperature was adjusted to 80 ° C. Using a fluorine-coated stirrer, the mixture was vigorously stirred for about 4 minutes so that air bubbles were taken into the reaction system at a rotation speed of 900 rpm. Thereto was added 26 parts by weight of 4,4′-methylenebis (o-chloroaniline) (made by Ihara Chemical Co., Ltd., Iharacamine MT) which was previously melted at 120 ° C. and filtered. After stirring for about 1 minute, the reaction solution was poured into a pan-type open mold coated with fluorine. When the fluidity of the reaction solution disappeared, it was placed in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane resin foam block. The polyurethane resin foam block was sliced using a band saw type slicer (Fecken) to obtain a sheet-like polyurethane foam. Next, this sheet was subjected to surface buffing to a predetermined thickness using a buffing machine (Amitech Co., Ltd.) to obtain a sheet with adjusted thickness accuracy (sheet thickness: 1.27 mm). The average bubble diameter on the grooved surface of this sheet was 45 μm, specific gravity 0.86 g / cm ³ , hardness 53 degrees, compression rate 1.0%, compression recovery rate 65.0%, and storage elastic modulus 275 MPa.

  The buffed sheet was punched to a diameter of 61 cm, and concentric grooves with a groove width of 0.25 mm, a groove depth of 0.40 mm, and a groove pitch of 1.5 mm were formed on the surface using a groove processing machine. The feed speed of the grooving blade at that time is No. shown in Table 2 below. 1 was used. The surface roughness of the obtained grooved surface was measured to evaluate the groove shape, surface burrs, and grooved blade wear, and the results are shown in Tables 1 and 2 below. Using a laminator on the opposite side of the grooved surface of this sheet, a double-sided tape (Sekisui Chemical Co., Ltd., double tack tape) was applied, and a corona-treated cushion sheet (Toray Industries, polyethylene foam, Torepefu) , 0.8 mm thick) and buffed and bonded to the sheet using a laminator. Further, a double-sided tape was attached to the other side of the cushion sheet using a laminator to prepare a polishing pad.

Example 2
The grooving blade feed speed at the time of grooving is shown in Table 2 below. A polishing pad was prepared in the same manner as in Example 1 except that 4 was used. The surface roughness of the obtained grooved surface was measured to evaluate the groove shape, surface burrs, and grooved blade wear, and the results are shown in Tables 1 and 2 below.

Comparative Example 1
The grooving blade feed speed at the time of grooving is shown in Table 2 below. A polishing pad was prepared in the same manner as in Example 1 except that 11 was used. The surface roughness of the obtained grooved surface was measured to evaluate the groove shape, surface burrs, and grooved blade wear, and the results are shown in Tables 1 and 2 below.

  The obtained polishing pads of Examples 1 and 2 and Comparative Example 1 were evaluated by the above methods. The results are shown in Table 1.

  As is clear from the results of Table 1 above, the polishing pads of the present invention of Examples 1 and 2 have a smaller surface roughness (Ra) of the grooved surface and a number of scratches than the polishing pad of Comparative Example 1. It can be seen that it is small and has excellent polishing characteristics. In addition, it can be seen that the polishing pads of Examples 1 and 2 using the manufacturing method of the present invention have greatly reduced burrs on the pad surface due to groove processing.

  On the other hand, the polishing pad of Comparative Example 1 that does not use the manufacturing method of the present invention has a very high number of scratches, although the polishing rate is not lowered, and the pad surface burrs due to grooving are very large. It ’s bad.

  As described above, the feed speeds of the grooving blades of the polishing pads of Examples 1, 2 and Comparative Example 1 are No. 2 in Table 2. As shown in 1, 4 and 11. No. In Nos. 1 and 4, the feed speed of the grooving blade changes in stages. In No. 4, the feed rate is increasing gradually. In 1, it is increasing or decreasing. No. In No. 1, a time for setting the feed speed of the grooving blade to 0 at a position where the desired groove depth is reached is provided. In contrast, no. Reference numeral 11 denotes a conventional polishing pad manufacturing method in which the feed speeds of the grooving blades are all the same. The polishing pads of Examples 1 and 2 were No. As shown in 1 and 4, by changing the feed speed of the grooving blade stepwise, the cross-sectional shape of the groove becomes a beautiful rectangle, and a groove with less surface burrs on the machined surface can be obtained. No. 1 of the polishing pad of Example 1 In the case of a constant feed speed as shown in FIG. 11, the cross-sectional shape of the groove does not become a beautiful rectangle, and the processed surface has a lot of surface burrs.

It is a schematic sectional drawing of one embodiment of the groove | channel provided in the polishing layer of the polishing pad of this invention. It is a schematic sectional drawing of the groove | channel provided in the polishing layer of the conventional polishing pad. It is an expansion schematic diagram of the blade edge | tip of the groove processing blade used for the manufacturing method of the polishing pad of this invention (FIG. 3-a front view, FIG. 3-b side view). It is an expansion schematic diagram of the blade edge | tip of the groove processing blade used for the manufacturing method of the conventional polishing pad (FIG. 4-a front view, FIG. 4-b side view). It is the expansion schematic of the blade edge | corner part before and behind use for demonstrating the test method of grooving blade abrasion.

Explanation of symbols

1, 2, ... groove
11, 21 ... side surface of groove processing surface,
12, 22 ... bottom surface of groove processing surface,
23 ... Swelling.

Claims (6)

  A polishing pad formed of foamed polyurethane having a groove in a polishing surface, wherein a processed surface of the groove composed of a side surface and a bottom surface of the groove has a surface roughness (Ra) of 10 or less.   The polishing pad according to claim 1, wherein a processed surface of the groove has a surface roughness (Ra) of 1 to 9.   A method for manufacturing a polishing pad, comprising: forming a concentric groove having a rectangular cross-sectional shape on a polishing surface by mechanically changing a feed speed and a feed amount of a grooving blade stepwise.   The manufacturing method according to claim 3, wherein, in the step of forming the groove, a time for stopping feeding is provided at a position where the groove processing blade reaches a desired groove depth.   The manufacturing method according to claim 3, wherein a feed speed and a feed amount of the grooving blade change stepwise and sequentially increase. The manufacturing method according to claim 3, wherein the polishing pad is formed from foamed polyurethane.

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